This invention relates to a hydraulically controlled bulldozer-blade attachment, particularly for application to an endless track tractor. This bulldozer-blade attachment can also fulfil the tasks of grading and shaping of soil or of snow-ploughing.
Bulldozer-blade attachments are known, which comprise a sturdy blade carried by the front section of a tractor, and said blade, in addition to being both liftable and depressable relative to the resting plane of the tractor on the soil, can be position-adjusted on three different planes. A kind of bulldozer-blade attachment of the kind referred to above is shown, for example, in the U.S. Pat. No. 3,882,751.
Such a type of bulldozer-blade attachment provides a supporting frame which can be secured to the tractor, a blade-carrier frame and three intermediate frames which linkably connect the blade-carrier frame to the supporting frame. More particularly, a first intermediate frame is linked to the supporting frame, relatively to which it can swing about a horizontal axis which is transverse to the direction of advance of the tractor, a second intermediate frame is linkably connected to the first intermediate frame with an axis of oscillation which is both vertical and central, whereas a third intermediate frame is linkably connected to the second intermediate frame with an axis of oscillation which is horizontal and is transverse to the direction of advance of the tractor, and the blade-carrier frame is linkably connected to the third intermediate frame with a horizontal central axis of oscillation arranged in the direction of advance of the tractor. The blade-carrier frame and each of the intermediate frames are connected via double-acting hydraulic jacks to the supporting frame and to a preceding intermediate frame, respectively.